There is NO predilection for homosexual preference in other species. Some aniamals, chimps for instance, may mount another male but it was consistently either just a display of dominance or in reaction to nearby stimuli (e.g. a female chimp in heat that just happened to be nearby). In other words, the animal had no clue what it was doing.
Mallards are known engage in necrophilia, and mothers in the animal kingdom frequently abandon their 'weak' children.
Perhaps Nat-Geo isn't the best place to look for morality?