Short answers, pulled from the story.
A single human being carries exactly fifty percent of their genetic code from one parent and fifty percent from another. This mathematical certainty forms the foundation of parenthood and has existed since the dawn of sexual reproduction.
Every sexually reproducing creature that is not a genetic chimera possesses a maximum of four genetic grandparents. This lineage continues with eight great-grandparents and sixteen great-great-grandparents, forming a tree that expands exponentially with each step into the past.
The evolutionary theory of parent-offspring conflict was proposed by Robert Trivers in 1974. This theory extends the more general selfish gene theory to explain observed biological phenomena such as siblicide in bird species.
Modern science utilizes polymerase chain reaction and restriction fragment length polymorphism to establish genetic fingerprinting with near certainty. While older methods relied on ABO blood group typing or the analysis of various proteins and enzymes, current techniques provide precise proof of biological fatherhood.
In Europe, parents are generally happier than non-parents, with happiness increasing significantly in the year before and after the first childbirth. The joy of parenthood does not necessarily scale with the number of children, as having higher-order children is not associated with further increased well-being in women.