A few years ago, when he was in his early 30s, Tyler Levy Sniff took a home DNA test he received as a gift. The results revealed a staggering truth: His father wasn’t biologically related to him. Levy Sniff confronted his parents, who explained that after years of trying and failing to have a baby, they turned to a sperm donor. Following the standard advice at the time, they decided not to tell him for fear of driving a wedge into their family.

Levy Sniff felt as if he’d found a key to his identity that he was looking for. “It made sense of why I felt different from my family,” he said recently. He wanted more information about the person he called his “bio father” to understand his genetic heritage. “It was so important to me to know my bio father’s life story, his personality and talents and struggles,” Levy Sniff says.

But by the time he found his donor, through relatives on two genealogy websites, the man had died — another revelation that shattered him, he says. To Levy Sniff, the value of knowing where you come from is self-evident. “A lot of influence comes from your biology,” he says.

There’s plenty of support for this way of thinking. Recent findings in behavioral science show the role of genetics in shaping certain individual characteristics. Questionnaires from doctors routinely ask for generations of family medical history. And learning about your genetic ancestry can be emotionally powerful — one reason millions of people buy inexpensive at-home DNA tests and sign up for genealogy websites.