The instant our children are born, we look for reflections of ourselves in them. When Evie Crosby, of Tallahassee, Florida, delivered her son, Wyatt, she immediately asked her husband, Adam, "Does he have your chin?" Adam gave her a thumbs-up as the nurses cooed over Wyatt's deep cleft -- just as nurses had done when Adam was born 30 years earlier. Moments like these are more than a little profound. Seeing yourself -- and your spouse -- in your baby makes you truly feel like a family. Inheritance goes far beyond eye and hair color: Genes can even shape personality traits like leadership and spirituality. Despite startling advances in genetics, our understanding of how genes and environment interact is far from perfect. "Many traits have a large hereditary component, but genetics isn't destiny -- genes are just one influence on how kids turn out," says Joann Bodurtha, MD, professor of human genetics at Virginia Commonwealth University, in Richmond.
It's easiest to spot similarities in your child's appearance. "Our 2-1/2-year-old daughter, Amber, is really a mix of both families," says Rose McKinney, of Oshawa, Ontario. "She has my face and my grandmother's stick-straight hair, but her dad's brown eyes and long, big toes." Amber's eye color isn't surprising: Brown eyes are considered a dominant trait, so if one parent has the gene for brown and the other has a recessive gene for blue, brown usually wins. Even so, nobody can predict eye pigment for sure: In some cases, both parents have blue eyes but still have a brown-eyed baby, which shouldn't happen if the trait followed the simple dominant-recessive rule.
"Most traits are actually determined by many genes working together, rather than a single gene," says Kate Garber, PhD, director of education in the department of human genetics at Emory University School of Medicine, in Atlanta. Take hair color, for example. If a father carries only a dominant gene for brown hair and the mother carries only a recessive gene for blond, their children should all have brown hair, but some of their grandchildren are likely to be blond. Reason: The kids inherit both sets of genes, which can combine with blond genes from their mates to produce fair-haired offspring. But don't blame the mailman if your child's hair is surprisingly red -- the interplay of genes can create all sorts of unexpected traits. And if your son eventually loses his hair, he can point a finger at either parent: Contrary to popular belief, the dominant gene for male-pattern baldness can be passed down by moms or dads.
Joseph Chisolm, of Secaucus, New Jersey, certainly knows how arbitrary inheritance can be. He's black and his wife, Donelle, is white, so they weren't surprised that their first child, 4-year-old Jaydon, was dark-skinned and brown-eyed. "He could pass for Hispanic," Chisolm says. But their 1-year-old son, Jordon, is startlingly different: "He's white, blond, and blue-eyed," says Chisolm. "You would never guess that he was the child of a mixed-race couple."
Even when your kids don't look exactly like you, there may still be subtle but striking resemblances. One study found that families tend to have similar facial expressions when they're happy, sad, angry, disgusted, surprised, or thinking hard. And kids don't just pick up these reactions from watching us: Blind members of 21 families in the study also grimaced, smiled, and scowled like their relatives 80 percent of the time. Other likenesses are quirkier. Both Kim Whorton, of Birmingham, Alabama, and her daughter Zoe, the oldest of 3-year-old triplets, have dimples in their shoulder blades -- a rare trait that's been traced to an abnormality on a specific chromosome.
In some cases, one genetic trait may be linked to others. Check the hair whorl at the top of your child's head: If it swirls counterclockwise, he has a 50-50 chance of being left-handed or ambidextrous, which suggests that both hair pattern and handedness are driven by some of the same genes.