What is "three-quarter sibling"

alt. 1 A sibling with whom or which one shares about 75% of one's genes. 2 # (context horse breeding English) The offspring of a horse's sire/dam that is by/out of a sibling of its other parent.Carol W. Mulder, "", ''Arabians Today'', 1986 3 # (context horse breeding English) The offspring of a horse's dam and a son of its sire. 4 # (context horse breeding English) The offspring of a horse's sire and a daughter of its dam. n. 1 A sibling with whom or which one shares about 75% of one's genes. 2 # (context horse breeding English) The offspring of a horse's sire/dam that is by/out of a sibling of its other parent.Carol W. Mulder, "", ''Arabians Today'', 1986 3 # (context horse breeding English) The offspring of a horse's dam and a son of its sire. 4 # (context horse breeding English) The offspring of a horse's sire and a daughter of its dam.