Or it can refer to a disease. Huntington's disease, for instance, is a dominant mutation where, if one is carrying that version of the Huntington gene, that mutation, that dominant mutation, will give the individual the disease regardless of what that person's other Huntington's disease gene allele is.
That other Huntington's disease gene allele can be perfectly normal, but the person still has the disease because of that one copy of the Huntington's disease gene that is mutated. That is dominance. Christopher P. Austin, M. Featured Content. Yet research has also found that most people with perfect pitch started taking music lessons before age 6, and that only 3 percent of people who started voice lessons after age 9 have perfect pitch -- suggesting that both genetics and training affect one's singing voice.
Average IQ scores have gone up in the past 50 years thanks to changes such as better early-childhood education, experts say, not because we're innately smarter. And intelligence may run in families partly because bright parents tend to provide a richer learning environment -- by having more books, for example. In fact, two recent studies found that the IQ of firstborn children is slightly higher than that of their younger siblings -- possibly because they received more undivided attention.
For example, your child could have genetic potential for a high IQ, but if you drank alcohol during pregnancy, it may be lower. Sometimes, our children pick up traits we don't intend to teach -- just by living with us. Nora Flanagan's 1-year-old son, Kevin, was adopted but has definitely taken on some family traits. He also has a boisterous laugh that leaves him out of breath, just like both of his adoptive parents.
We all know that having a family history of an illness can put a child at risk. Some diseases, such as cystic fibrosis and hemophilia, are directly caused by an abnormality on just one gene. However, most conditions involve multiple genes and complex traits that may increase a child's risk but not automatically doom him to developing the disease down the road. Type 2 diabetes is strongly genetic: If you have it before age 50, your child has a one-in-seven chance of developing it as well.
However, people in non-Western countries who eat better don't get diabetes as often, which shows that lifestyle can reduce the risk. Similarly, genetics account for an estimated 75 to 80 percent of the difference between a skinny kid and an obese one, but even if a child has "fat genes," he can avoid weight-related problems like heart disease if he has healthy habits. For example, if your father had skin cancer and your child has strawberry-blond hair, you should be extra vigilant about using sunscreen.
Parents with a history of depression can be on the lookout for symptoms in their kids and get them help as soon as possible -- if the condition ever occurs. And that's a big if. Whenever parents say, 'My child is just like me,' they usually qualify it by saying 'except for Scientists used to think people had up to , genes -- until the Human Genome Project revealed that we actually have closer to 25, Why the huge overestimate?
It turns out most genes are multitaskers and do their jobs by marshalling other genes -- turning them on and off or boosting their effects -- so we need fewer genes overall. As a result, few characteristics can actually be traced back to a single gene there aren't enough genes to go around for that.
Nevertheless, kids have a greater chance of inheriting some characteristics rather than others. Here are some of the traits you're most likely to pass on. Used with permission from the September issue of Parents magazine. In addition to causing disease, the sickle-cell allele makes people who carry it resistant to malaria, a serious illness carried by mosquitos.
Malaria resistance has a dominant inheritance pattern: just one copy of the sickle cell allele is enough to protect against infection. This is the very same allele that, in a recessive inheritance pattern, causes sickle-cell disease!
People with two copies of the sickle-cell allele have many sickled red blood cells. People with one sickle-cell allele and one normal allele have a small number of sickled cells, and their cells sickle more easily under certain conditions. So we could say that red blood cell shape has a co-dominant inheritance pattern. That is, individuals with one copy of each allele have an in-between phenotype.
So is the sickle cell allele dominant, recessive, or co-dominant? It depends on how you look at it. If we look at the proteins the two alleles code for, the picture becomes a little more clear. The affected protein is hemoglobin, the oxygen-carrying molecule that fills red blood cells. The sickle-cell allele codes for a slightly modified version of the hemoglobin protein. The modified hemoglobin protein still carries oxygen, but under low-oxygen conditions the proteins stick together.
When a person has two sickle cell alleles, all of their hemoglobin is the sticky form, and the proteins form very long, stiff fibers that distort red blood cells. When someone has one sickle-cell allele and one normal allele, only some of the hemoglobin is sticky.
Non-sticky hemoglobin is made from the normal allele, and sticky hemoglobin is made from the sickle-cell allele every cell has a copy of both alleles. The protist that causes malaria grows and reproduces in red blood cells. Just exactly how the sickle-cell allele leads to malaria resistance is complex and not completely understood. However, it appears that the parasite reproduces more slowly in blood cells that have some modified hemoglobin. And infected cells, because they easily become misshapen, are more quickly removed from circulation and destroyed.
To see more examples of how variations in genes influence traits, visit The Outcome of Mutation. Dominant and recessive are important concepts, but they are so often over-emphasized. After all, most traits have complex, unpredictable inheritance patterns. However, at the risk of adding even more over-emphasis, here are some more things you may want to know:.
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