Asthma is neither a communicable disease nor has any genetic heredo-familial trait! As a parent, make sure that your children do not have the environmental constraints that you had! DO NOT USE COTTON MATTRESSES & PILLOWS!( They harbour huge quantities of Dust Mites!) Make sure they get good aerobic exercise right from childhood( Yoga, Surya Namaskar, Swimming etc), introduce your baby to all goods within first year of life. Do not use ultra-clean drinking water...Boiled and cooled water will do (the dead germs in them will act like vaccines to protect them against most common pathogens), give them plenty of probiotic rich foods like yogurts.