Where is DNA?
DNA is in the nucleus of all your cells, except mature red blood cells. These blood cells are the only part of you that have no DNA because they lose their nuclei as they fill with hemoglobin. All of your other cells contain exactly the same DNA in each one of them.
How much DNA do I have?
If you stretch it out, you have about 3 feet of DNA packed into every cell nucleus - that's like 30 miles of incredibly fine fishing line stuffed into a blueberry!
How can my grandchildren have blue eyes if my daughter and her husband have brown eyes?
Everyone gets half of their genes from their mother and half from their father. If you look at your parents and grandparents, you can see how certain traits have been passed on through your family. Inheritance is not really a blending of traits; it is a process of passing on discrete units of information, called genes. Some genes always express themselves ("dominant"), but others do not always ("recessive.") In general, dark eyes are dominant over light eyes. Dominant traits always show up (are "expressed"), whether you have one or two dominant genes for the trait. Recessive traits are hidden by dominant traits, and can only show up if you have two recessive genes for that trait. If a parent has blue eyes, they have two blue genes, while a brown-eyed parent could have either two brown genes, or one brown and one blue gene. So two brown-eyed parents could each have a blue-eyed gene that they would pass on to their child, who would have blue eyes! When you pass on your genes to your child, the expression of those genes depends upon what genes were inherited from each parent.
If I have a gene for a disease, will I get it?
Not necessarily. Genes don't always equal destiny. Genes only indicate the chances that an individual will get certain traits or conditions. Genes may also predict how a living thing will react to its environment. Given an individual’s genes, we can make some predictions about it and its offspring, but the genetic predictions are not a guarantee. An individual’s environment, including exercise and nutrition, are also important in determining traits and conditions. Understanding how your genes work together with your environment can help you figure out how to live a better, healthier life. Some diseases are caused by genetics; others are caused by environmental factors. Many diseases or conditions fall somewhere in the middle. But what if a certain trait "runs in the family,” does that mean you or your kids will definitely get it, too? No. Genes are a big part, but only one part of what makes you who you are. Your environment and personal habits are two examples of what else can help determine what makes you, you.
