Board Thread:Questions and Answers/@comment-27176987-20160913054504/@comment-25942629-20160915134242

As far as we know, there is nothing indicating that those two people are not his real parents, but it's a possibility. Just because they are related is no reason for a person to be kind to their children. Child abuse is common, especially when the kids are too small to fight back. Just last month, I had a 4-month-old patient whose dad abused him enough to give him shaken baby syndrome, and the baby could no longer raise his head or turn over. He had to be on a ventilator for a while. Although he could breathe on his own by the time I saw him, he had an feeding tube going into his stomach because he couldn't swallow anymore.

Biology is no reason for a parent to love a child. As a matter of fact, abuse is typically worse against a woman while she's pregnant than when she's not.

Abuse is not uncommon.

As far as Yu's gene goes, there are two distinct possibilities: 1) he inherited it from an ancestor, or 2) he was genetically modified by someone. That being said, it's possible that this might be a trait rather than a gene, and he has the phenotype for it while his parents only have the genotype.