Experts say twins, triplets, and quadruplets share a lot of the same DNA, but it’s their environment that really shapes who they become.

When Nick, Nigel, Zach, and Aaron Wade were born, their parents were likely filled with emotions of excitement, joy, and jubilation.

After all, successfully bringing healthy quadruplets into the world is feat enough for one lifetime.

But the boys, who live in Ohio, weren’t finished impressing their parents — or the world, for that matter.

Earlier this month, the 18-year-olds announced they’re heading to college together. And not just any school.

They’ll be attending classes at Yale.

The brothers, who were accepted to 59 other schools, are fraternal quadruplets.

That means that while they were all carried by the same mother at the exact same time, their genes aren’t the same. They aren’t identical quads.

They’re unique — in looks, personalities, and DNA.

The Wades’ father, Darrin, is a software architect for General Electric. Their mother, Kim, is a junior high school principal.

So, which parent can the boys thank for their Ivy League-level intellect?

Well, either.

Read more: What it’s like to raise quadruplets »

When it comes down to who you are, you’re not just the result of 3 billion DNA pairs.

Sure, each DNA pair makes a “decision” about who you will be — height, hair color, diseases. But that’s just the nature part of the equation.

Those inherited genes aren’t the only decision makers in your life.

Your environment — the people who raised you, your friends, your life choices — nurture you, too. They help shape who you will be.

Perhaps the best way to see this nature vs. nurture rivalry is to look at twins or multiples.

“Traits, physical and psychological, are heavily influenced by our genetic composition. Therefore, our children would inherit a mixture of mom’s and dad’s traits,” Dr. Manuel Orta a pediatrician at Palmetto General Hospital in Florida, told Healthline. “However, most genetic expression, in particular what’s related to psychological aspects, are heavily influenced by our environment and our life experiences, even when these seem to be insignificant. In the majority of cases of multiple babies, each has a unique combination of traits, but the final result and expression of these traits will depend on external factors.”

Read more: What to expect when you’re pregnant with triplets »

Multiples — whether they’re identical or not — often experience a similar environment for the first 18 or so years of their lives.

In most cases, they’re exposed to the same people, same schools, and the same opportunities.

Despite this parallel rearing, these children can end up quite different in many ways.

“Studies show that identical twins who have been separated at birth share different characteristics and behavioral traits depending on the environment in which they were raised,” Jeanne Dockins, a nurse and mother of 24-year-old twin boys, told Healthline. “An individual’s environment, thoughts, beliefs, and attitudes affect their behavior.”

In her own life, Dockins has seen this tug-of-war play out between her two sons.

“One spent more time with his father, who is money and success oriented. My other son spent more time with me. I am more service oriented,” she explained. “The one twin who is more like his father looks for his happiness and status in life by his bank account balance and the things he has in life. He currently buys and sells autos. The other twin, although he likes money, his self-worth is not defined by it. He has a job with an airline and sells merchandise by fulfillment for a larger internet retailer.”

This is a story that many mothers of multiple birth siblings repeat again and again. Their kids are similar in some ways, but they each are quite unique.

Heather Nelson, an author, columnist, and mom to 6-year-old twins and a 7-year-old child, saw differences in her twins “almost instantly.”

“They had different sleep patterns and food preferences. Different things made them giggle as babies, and they needed and liked different types of affection and interaction,” the Connecticut mother told Healthline.

Nelson sees firsthand many of her children’s developmental milestones because in addition to being their mother, she’s also their teacher.

“We made sure that all three kids understood everyone has differences and different strengths, and likes and dislikes, from the beginning,” she said. “They don’t even notice their differences as anything other than being the way God made them.”

Ann Taylor Pittman, an author and magazine editor, is the mother to twin boys, too.

Like the other moms interviewed for this story, Pittman said her sons began showing their unique personalities early.

“Daniel has always been a stubborn little thing — always,” Pittman told Healthline. “Connor, on the other hand, has always been a people pleaser. So as toddlers, when Daniel would get in trouble, he would not apologize or admit that he had done anything wrong. Connor, though, would be eaten up and would apologize and try to make things right. Daniel is refreshingly laid back about most things. I think this is because of his physical challenges [Daniel has cerebral palsy and scoliosis]. He has been through and continues to go through some really hard things; he has to always work far harder than other kids just to keep up, physically.”

Those traits — Pittman said — she can pinpoint directly to herself and her husband.

“Daniel is more like Patrick — more spontaneous, laid back, happy to march to the beat of his own drum, and with moments of pure genius,” she says. “Connor is like me — wants desperately to please others and be accepted by others, filled with anxiety and self-consciousness, always second guessing himself, and smart more because he’s a rule-follower than a natural genius. He likes order and schedules and doesn’t do great with spontaneity.”

Read more: What do you want to know about parenting? »

Science can tell us a lot about who we are.

Our genes possibly predestine us for specific behaviors or appearances, abilities, or skills. Our genes may even influence how well we learn or what we’re eventually attracted to when it comes to careers, foods, even partners.

Ultimately, however, our genes may not have the final say. Our environments have a significant ability to influence each person.

Twins, triplets, and other multiples are perhaps the greatest example of this.

Though they often share similar or even identical genes, they’re never the same person. Life has far too great an impact on them to guarantee that genes — the things we all inherit from our parents — have the final say in who or what we become.

“Any child is a mixed bag and a total crapshoot on which traits your kids will get from you,” said Nelson. “Personality and characteristics are still largely a mystery to us, I think, which is good. I love the unique adventure that children bring in their individuality.”