Can I crossbreed my horses?
The simple answer to this is YES! All horses are able to be crossbred on HEE. The breeds you cross will determine what breed your foal will be. The following list is from the game's FAQ:
WB sire X WB dam = WB foal
TB sire X TB dam = TB foal
WB sire X TB dam = WB foal
TB sire X WB dam = SH foal
SH crossed with anything except ISH = SH foal
SH crossed with ISH = ISH foal
RID (sire or dam) x RID = RID
RID (sire or dam) x anything = ISH
ISH (sire or dam) x anything = ISH
KNN sire X KNN dam = KNN foal IF a filly has LP or a colt has LP and PATN. If a foal doesn't meet these criteria, it will be a SH
RID or ISH sire X KNN = ISH
KNN sire X RID or ISH dam = ISH
KNN sire X anything not KNN, ISH, or RID = SH
Any sire not KNN, ISH, or RID X KNN = SH
AA sire X AA dam = AA
Any AA x TB = AA
X sire with X dam = X
Any X with TB = X
PON x Anything = PON if the foal 14.2 hands or under
PON x Anything = SH if the foal is over 14.2 hands
Any cross that results in a SH normally will result in a PON if the foal is 14.2 hands or under