Hello! Keloid is harmless skin disease, commonly occuring on chest. Keloids are of two types.. Idiopathic ( without cause) and secondary to injuries, burns etc. your wife has idiopathic variety. But whatever it is, It is not infectious, so you will not get keloid, However, it can occur in any person. But , your sexual life or your health will not be affected by the keloid of your wife.... It is not inherited disease, but still, there may be tendency to develop in your kids. Intralesional steroid, hyaluronic acid gel will be helpful to reduce the size... Ok , do not worry, Be happy.