请问在家排行老几用英文怎么说？

what's your seniority among your brothers and sisters?

Be at home seniority among brothers and sisters order of seniority among brothers or sisters

the order of seniority among his or her brothers or sisters in one's family

老外不这样问的~所以你生硬地翻译了,他还听不懂,不如意译!~
经常说:"Are you the only child in your family?" 你是独生子吗?
"Do you have any brothers or sisters?"你有姐妹或兄弟吗?