Uhg, female Tormods, dying sperm and patterns of similarities in random propagation...
It's not that the weaker sperm die, it's that the stronger swimmers get there faster. Even then, it is not a first come first serve basis. The sperm carry a chemical on their tip that breaks down a barrier, so many of them are needed for one to penetrate the egg. If just one sperm gets there, as they might tell you in school, you're not likely to become pregnant. However, it's likely that if one gets there, he has a bunch of homies with him
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There may be similarities in patterns you've observed in your family and others, dependant on what sex child was born first. However, the process is entirely random. Any similarities you observe, are coincidence. Choose a larger group to study and make sure you're not reading into it. It's random because each sperm and each egg are formed uniquely through a process called meiosis. The observed similarities between parents are because the genes inhereted by each sperm or egg are replicas of each parent. Each has half of the DNA of each parent's normal cells. So when you combine them, you get the total number of 23 pair of chromosomes that all healthy humans have.
Also, the sex of the child is fully dependant on the father and has nothing to do with the mother's egg. This is because the mother only produced the X chromosome, while the father produces both X and Y chromosome sperm. Therefore, his Y chromosomes are needed to produce a son (XY combination).... whereas his X, if it reaches the egg, will produce a daughter (XX combo).
