Again, jumping to conclusions without reading the story -- pro tip, TTT, actually read the article (or at least be aware the salient points) before commenting.
The three children were conceived by and born into a family with a mother and a father, at the time in a stable relationship. Since then, however, the mother and father split up, and the mother has now ended up in a relationship with another woman. As I commented earlier, they are well aware of the circumstances and have even considered that the same-sex relationship has played its part. Given the two elder brothers, neither of whom has shown the same inclination, there's no evidence of this. Time alone will tell if it's just a phase, a reaction to the unusual circumstances, or something real. In the meantime, it's doing no-one any harm so what's the problem?