a lot of details are open about her though i think he'd need to be 21ish if that's okay? karl, jac, and another sister were born pretty close to each other as far as i remember. karl and jac were both born in sydney, their family spent most of their childhood travelling to make nature documentaries kind of like the wild thornberries (but their mom presented) but i think a lot of their travelling was in australia, though we did work out a rough timeline of where they were most years. anyway, jac moved to america in her mid teens and karl moved when he was 17 for college. he went to california and jac did originally when she moved first but ended up in austin sooner than he did, karl only moved there threeish weeks ago. their mom is actually american and from austin (their dad is australian) and i'm sorry if this is kind of all over the place we probably have more details than anyone needs about their family tbh and i can add you to the family custom if you're still interested after this AND IF NOT we can definitely work something else out instead!