Kronos the Titan Lord wanted to eat all his kids. But Zeus's mother, Reah, saved Zeus and later Zeus fed his father a mixture of wine and mustard which caused him to barf up all his kids (Poseidon,...
It has been happening as young as 12, and sometimes is reported even earlier.
They would be a second cousin, once removed.
yes...
It is 50-50. The gender of any child is always 50-50, as previous children have no impact on what you will have next.