edward mccabe: genes are like beads on a string. those strings are then pay into the chromosomes, and we inherit one set of chromosomes from our father, one set of chromosomes from our mother. genes direct the formation of tissues and organs, hold instructions for all the chemical reactions that occur in the cells, and play a crucial role in determining our health and how long we live. in terms of appearance, a lot of how we look is in our genes. all we need to do is to look at two identical twins to realize how genes are important for our hair color and our eye color and the shape of our nose and the shape of our mouth, how we carry our fat, how tall we are, how short we are, the shape of our bodies. all of these are controlled-- about 90 or 95% by our genes. when we start talking about internal things, your personality, who you are, whether you're a nice person or a not so nice person, whether you have a good sense of humor or are rather dour-- then genes are also important, but to a lesser extent. clearly these aspects of our per

edward mccabe: we know from the studies, kids who take drugs, kids who are involved in gangs, are more likely to be involved in violent acts. we tend to sometimes not be as sensitiveo these issues. we can't predict every violent act, but when there are signs ahead of time, we need to recognize that maybe we need to try and get some help for those individuals. the adolescent physicians are very good at talking to those kids and helping to identify which kids are at higher risk than others. so that i think that we need to use the appropriate health professionals to try and help us do a better job. parents face a wide range of health issues as their child matures. the baby with the runny nose, grows into a teenager who rarely has a bad cold, but is confronted with health issues such as smoking and alcohol. as they grow, children learn about health by what they see around them. kids learn better by example. we can say as much but the first two best role models are the-- you know, the people or the parents that are in the home. "the human condition" is a 26-part series about health and well