I do think familial comparisons are actually appropriate in Torchwood, to an extent. I mean, Owen obviously has this whole daddy issues thing going with Jack, and Jack sees Owen as his wayward little brother, to some extent (Although—right there. You notice that? The familial relationship is different from Owen’s point of view than from Jack’s.). And Jack sees the team in general as his children, to varying degrees. But, that doesn’t mean they are his children. Jack is not Owen’s father, and Owen is not his little brother. There are elements of that in their relationship, but it is not the sum of their relationship. Which is to say, Jack and Owen have a platonic relationship in canon with familial elements, but the familial elements are not great enough to keep the relationship platonic (the Owen in my head is actually very straight, hence the platonicness, but that could just be me). It’s just not. They are not related. They don’t perceive themselves as related. They don’t even act like they’re related, most of the time. It’s just once in awhile, Owen gets his daddy issues into the relationship, and Jack gets his I-lost-my-little-brother issues into the relationship. Those issues might make having sex awkward, but they might not. It’s hard to judge. People are more complicated than that.
(Although…who gets forgiveness and a hug at the end of Season 1? And who gets forgiveness and a hug at the end of Season 2?)