Unless you are ejaculating into one of your family members vagina's....it's not likely.
This question pops up on this site from time to time, (occasionally looking like it was posted by the same guy over and over in fact). Either it is a common fantasy, or just a very persistent poster. If a person masturbates in the privacy of his own room, that is where the semen will stay. Sperm dies quickly when exposed to air and no longer at body temperature. Normal precautions for privacy will keep there from being any issue.