The chemicals responsible for the taste of both goat and mutton are in abundance for mature sheep and goats. Its a hormonal thing that isnt present in lambs , when butchered at weights younger than their maturity (usually a market definition for a "lamb" is anything under 110 lbs hanging weight). Its not at al a matter of taste , i8ts a matter of fact . MAybe you are not a genetic "taster" of he mutton "tallow". Im not sure of the actual chemical name but I suppose , if I spent some time< i could find its name.
We have mature sheep made into a kind of "sweet lebanon" baloney. When I take some od sheep to the butcher, the bitcher will carefully debone and remove ALL fat and fell from the met cuts and then cook them with spices. That is blended with about 50% pork and sweet cure. The result is a baoney that is so spicey as to kil any remnants of the tallow taste. Its quite good but was made after many attempts at cooking the meat without careful cutting and removal of any grictle and tissue and fat.
Without any spirit of rancor, nor do I wish to stir any pots of verbal retribution, Im only stating a fact. DO with it as you please.