Do sports dynasties rest on the power of genetics, smart parenting, or a combination of both?

The Kansas City Royals’ first round drafting of Bobby Witt Jr. came as no surprise to most analysts. In an overly conventional draft, Witt Jr went second overall. What made the high schooler’s draft significant was that his father Bobby Witt Sr. went to the Rangers in the first round of 1985 and went on to pitch for 16 seasons. It marks only the seventh time in history that both father and son went in a first round. This infrequency should not, however, cloud the frequency with which familial sports dynasties occur.

Major League Baseball has seen no shortage of familial dynasties. Although it may seem natural for a son to follow in his father’s footsteps, going pro in a sport requires more skill and preparation than following one’s father as a fireman, electrician, police officer, or even doctor.

According to Baseball Almanac, there have so far been 237 sons who followed their fathers into the majors. Many of these families, such as the Boones and Ripkens, included multiple members and generations.

Currently, Vlad Guerrero Jr. represents the highest-profile MLB progeny. Signed with the Toronto Blue Jays in 2015, he racked up 192 runs and 209 RBIs in the minors in 1,075 plate appearances. The Blue Jays called him up in April, and after a slow start, he is currently hitting .248 with a .762 OPS.

Vlad Jr. has some serious boots to fill. His father was a nine-time all star, 2004 American League MVP, and was inducted last year into the Hall of Fame. Other top players today whose fathers also played include Lance McCullers Jr., Cody Bellinger, and Adalberto Mondesi.

But making the pros is a steep hill for youth athletes. A 2015 study showed that only one in 168 high school baseball players get drafted to the MLB. Although, I’m aware of no studies to show the rate of professional athletes’ children by comparison, more than two percent of MLB players this decade had fathers who made MLB rosters.

But do genes affect this success? Or does the environment that pro athlete fathers create provide the fertile ground that allows their sons to develop into pro ball players at a higher rate than electrician, plumber, and accountant dads?

To deny the genetic factor would be senseless. The ACTN3 and ACE genes do affect the fiber that builds muscle, which increases strength and endurance. Most professional athletes are bigger and stronger than most of the population; therefore, their sons are likely to look similar.

Geographic environment can also play a role. A study by the International Journal of Sports Medicine in 2015, led by Dr. Gavin Sandercock, a clinical physiologist at the University of Essex, concluded that a mother’s exposure to the sun’s rays positively impact muscle development in her child. Therefore, mothers in North America further away from the equator are best served—if hoping to raise an athlete—to conceive in late winter and give birth in October or November.

But the requirements of individual sports also matter. For instance, baseball and soccer players do not benefit nearly as much from height as basketball players; and in soccer, height can actually serve as an impediment. According to a British study of twins, height is 80 percent heritable, higher than most traits. Aerobic endurance is heritable at around 50 percent, but strength can vary from 30-83 percent. A Wall Street Journal study found that 48.8 percent of NBA players were related to someone who had played basketball at at least the NCAA level. By comparison, WSJ found that only 17.5 percent of NFL players and 14.5 percent of MLB players are related to someone who reached that level in their sports.

The expectation of athletic greatness passed through the gene pool can be overestimated—if for no other reason than because interest must accompany size and physical giftedness. If an athletic high schooler likes entrepreneurial or scientific endeavors, he’s less likely to put in the time necessary to hone his physical potential to sports.

Nothing could be likelier to cultivate interest in a sport than seeing one’s father gain wealth and fame competing in that sport. When looking at the success of father-son duos in the MLB, the nature aspect of a child’s upbringing deserves closer scrutiny, considering the limitations of genetic heritability of baseball aptitude.

Having an active father figure who sets a positive example represents an advantage in itself. Although, professional athletes often fall short in that aspect like fathers in any other profesion, they possess the advantage of having achieved success in the industry, and can therefore advise their sons how to avoid some of the hardships they faced on their way to the top.

Although everyone loves a good American success story about a kid who grew up in poverty and a broken home to overcome adversity, many pro athletes succeeded because they had the cookie cutter childhood.

“The reason I made it was because of two people – my parents,” said Matt Birk, a former Pro-Bowl center for the Minnesota Vikings and Baltimore Ravens. He listed a number things his parents drilled into him that shaped his future NFL career. Topping the list was “Go outside and play.” Although, this may seem cliche, in a child’s formative years today, this can mean the difference between becoming an athlete or a gamer in high school. The disappearance of the sandlot in American childhood culture is the biggest driver of diminishing American talent relative to other baseball cultures around the world. If kids play baseball for fun, they are more likely to want to take the risk of putting in the hours in high school to become a draftable athlete. Even if they don’t make it, they will still be able to fondly look back on those days as fun.

An athlete father who takes time to teach his son the craft of baseball also gives a kid the advantage of having a kind of in-house coach. Although many fathers unfortunately alienate many sons from the sport through this approach, a former athlete is more likely to know to strike the right balance between father and coach.

Former professional athletes are also less likely to fall into what University of Washington researcher Frank Smoll calls the “reverse dependency trap,” by which parents attach their own self-worth to their childrens’ success. It’s highly unlikely that a millionaire former MLB player would try to attone for missed opportunities through his son’s on-field feats. Can anyone imagine Vlad Guerrero pushing 15-year-old Vlad Jr. to improve his game with the subconscious reason that his son might also fail to win a World Series in his future career?

What ever balance Bobby Witt Sr. struck with his son, it appears to have succeeded in inculcating a genuine love for the game. Bobby Jr.’s high school coach Alan McDougal told Sports Stars of Tomorrow that Bobby Jr. and his father rarely miss a weekend to use the school’s facilities to work on his hitting.

“They’re so far ahead of where I was at this age,” noted former Texas Ranger Rusty Greer, whose son plays with Bobby Jr., “simply because of the training they have, the facilities they have, but then the desire they have as well.”

But making smart career choices can sometimes impact professional success in baseball as much as healthy practice.

Success in baseball relates similarly to success in business. The first-generation entrepreneur often struggles mightily. Furthermore, there’s no guarantee the entrepreneur’s offspring will inherit business sense or interest. But if the parent can succeed at both business and parenthood, his or her children will have a significant chance of leading a fulfilling life, doing what they enjoy. Likewise, the professional baseball player who succeeds even moderately at parenthood carries an advantage far greater than raw genetics over his neighbors in raising a professional athlete.

The nature of genes matter, but in baseball, the nurture of fatherhood matters more.