Can inheritance diagrams predict what my family will look like?
No. Many of us have seen diagrams like those shown above during our school years or perhaps in medical offices. Unfortunately, these diagrams very often lead to misunderstandings. The diagrams are mathematical calculations of the odds that one gene or the other in a pair of genes will be passed on to a child during any particular conception. These are the same kinds of calculations one would make if asked to predict the chances of a coin landing as heads or tails. With each coin toss (assuming the coin isn’t weighted and the conditions are otherwise impartial), the chances that the coin will land in one position or the other are 50 percent. In reality, if you were to toss a coin six times, you might come up with any number of combinations: All your tosses might be heads, or five could be heads with one tails, or four might be tails with two heads. In fact, every coin toss was a new set of odds: 50 percent heads, 50 percent tails. The second coin toss wasn’t the least bit influenced by
