So, if Kiya, Tut's mother was Tadukhipa, she had to be 11 or maybe 12 when she gave life to Tutankhamon. It's too early for an Egyptian, too, or not?
It's not at all unusual. Mothers in ancient Egypt were often only about 12 years old; husbands were often young teenagers. To this day people in the Middle East tend to mature physically (i.e., reach puberty) faster than many Westerners.
This was a time when people were lucky to live 40 years; many died at about age 35. Consequently people married very young and produced a family as soon as possible, and to the ancients this was all quite normal. Ancient Egypt suffered a significant infant mortality rate (in our own exhibit at the Field Museum we have the mummies of two babies and five toddlers, none older than 5 or 6), so it was sometimes necessary to have many children.
The royals tended to be married off at particularly young ages, and for two reasons: (1) to establish the pharaoh on the throne, and his wife along with him; and (2) to start producing children as soon as they were physically able to do so, always hoping for male heirs to the throne. Tutankhamun was about 8 or 9 when he ascended to the throne in 1334 BCE; almost a thousand years ealier Pepi II, last pharaoh of the Old Kingdom, was only around 6 when he was crowned.