A childs mother must file a petition for child support in the local family court.
No, but she can be your half-sister - if your sister marries your father or if your mother gives birth to you with her father (your grandfather).
Child support is paid until the children are 18.
If a man and woman marries, have a child together and the mother dies, then the man becomes a widowed father.
Oedipus kills his father and marries his mother.
Nothing changes regarding child support orders whether it is the mother or the father who is remarrying. The child/children are the responsibility of the biological parents not a new spouse. For example if the mother marries someone of substantial means it would not affect the child support amount that was ordered to be paid by the biological father, as the mother's new spouse has no legal obligation to support the child/children.
A stepmother is the woman your father marries after your mother. His stepmother packed his lunch for school.
Antigone's father/brother is Oedipus. (Oedipus marries his mother, Jocasta and Antigone is their child.)
Gel Electrophoresis is comonly used in paternity testing. It compares the father or mother's DNA to the childs DNA.