What could cause(childhood)in-toeing, knocknees, scfe, juvenile arthritis, meniscal tears when no one else in family has these issues?genes or enviro?

No unifying factor: There is no one origin for these separate issues. Knock knees is a natural finding in infants that usually self corrects with age unless sitting/sleeping patterns prevent it. SCFE are more common in heavy children whose weight places them at higher risk. Meniscal tears are triggered by events/trauma. The true origin of JIA is unknown but may have be influenced by genetics as well as environment.