I don’t believe cracked hooves are genetic. I agree with evaluating diet first and doing barefoot hoofcare with trimming and a mustang roll. An angled edge always seems to chip plus it interrupts the natural rollover of the hoof when the horse moves. How often is your horse trimmed? Most horses need a trim or good rasping every 5 weeks. Some can stretch to 6, but not really recommended. The hooves usually will start chipping after 6 weeks due to excess length. Same as our nails. All horses differ in how long they can go before chipping due to length, but excessive length creates many other problems too. Go to http://www.hoofrehab.com to learn about a mustang roll. Basically it is a rolled edge on the hoof wall like how a mustang naturally wears his hooves. I read about an equine hair mineral analysis that is supposed to be the best for diagnosing diet issues. Cost is $150 and is available through equine.uckele.com/equine-hair-mineral-analysis
Hope this helps!