Sure he always wanted a sibling,yes sure he pestered his mother when he was younger and yes sure his father wasn't around for 20 years so he never got a sibling but he wasn't mad about it,he had honestly forgotten about that he wished for a sibling

20 years later,there he was looking down at his newborn baby sister, apparently his mothers days weren't over yet apparently,his parents sure had fun after his father Odysseus returned from a 20 year adventure that had probably left him traumatised

" This is weird* Telemachus says, looking down at his new baby sister in the crib"what am i supposed to do with you? You're so small " he said picking up the newborn baby in his arms it was very weird for him to hold a baby since he wasn't used to it at all " Guess i got my wish granted a bit too late huh?" Telemachus says, Laughing "welcome to the word little seashell... Gods you look exactly like mom.. not a trace of father in your face.. that's actually good mother has to see enough of me being dad's twin anyway "