Inbreeding is exactly what it sounds like – breeding horses with a bloodline.
In Photo Finish™ LIVE, any horse can produce with any other horse, but the closer you are to each other in blood relationship, the much higher chance of disastrous breeding results. Starting with a hypothetical foal, FOUR (4) generations are all checked to see if any share a common bloodline. If ANY match, then there’s a chance of penalties. The farther away the match, i.e., a shared great-grandparent, the less likely and lower the severity of a penalty. But sharing parents with grandparents or breeding with siblings is, of course, a much riskier affair!
The screenshot from the Breeding Report gives you a quick view of the bloodline that matters for inbreeding.