The older that such fish become, the more mercury they may have absorbed. Anything that eats these fish within the food chain also consumes the higher level of mercury that the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher
The goal, then, when it comes to having a boy is to increase the likelihood that a Y chromosome sperm reaches the egg first. Many medical researchers believe that Y chromosome sperm are faster swimmers, but that X chromosome sperm have more endurance.
Theoretically you can have children at any age if you have sperm. But is that sperm going to give you the same genetic qualities as the sperm from a younger individual? We know that fertility does decline. We know that after the age of 30, there is a drop in testosterone of 1 percent a year. Testosterone is the energy, the hormone that you need to make good-quality sperm. It takes much longer for an older man to have children. But we havenât studied fertility of men in their 60s or older. Q: What does age do to sperm?