What causes you to have an attached kidney when no one else has it in my family? will my children have it to if husband don't have it but i do?

Confusing label : I have never heard or read of an attached kidney.They are sometimes fused & may be called "horseshoe"kidneys. Kidney defects arise in ~ 1/500 of the general population & are found in ~1/50 in close relatives of those found with a defect& often go undetected. The process is multifactorial & direct risk is probably about 5%. This is something pre or postnatal ultrasounds would easily detect.