Regardless of its origin, the term cis is used by the trans community, in particular non-binary and gender fluid member it seems, to attack and shoot-down debate with non-trans (i.e. cis) people. The term is used to suggest that because the individual is cis, he/she is privilaged in that they are in the majority and experience little oppression because of their gender. It is a term simply used to dismiss others and cause them to feel bad about their privilage in this new game of oppression-olympics that seems to have taken over the internet and universities. The term is used against gay men and women and other minorities who identify with their assigned-gender to suggest that they are stil privilaged in spite of their status as a minority and thus their opinions are those on non-trans, privilaged people and so should hold no merit - it is quite a sad term and is used more politically than just as a simple means of catagorization.

I read the same regarding being gay is more likely if one has an older sibling. I'm the youngest with one older brother. My uncle is also gay but he was the older one of him and my father (they were also a family of two boys like my own)

While I think you can indeed live a 'happy' life not being 'out' as gay, that happiness is only relative - i.e. you're only happy as far as you are aware, because you have not experienced being out and the happiness such might yield. Not coming out and experiencing the sheer ease of mind it gives you etc is also a happy experience; many would argue an experience happier than the one being lived by someone who is not out. However, because you are not out, you are happy but know no different and so you can't truly gage your happiness vis-a-vis being out. Only those who are out can truly say they are happier than if they were not or that they were happier when they weren't out because they have experienced both states. Your current state of happiness is only relative to what you know, and as you don't know how much happier/unhappier you would be if you were out, to say you are happy in a definitive sense is somewhat self-misleading. Your understanding of happiness will change should you come out and it may lead you to think you were happier before or happier after the fact. I'm certainly not agrguing that coming out would make anyone happier, and indeed I recognise that for certain people it may be highly likely that coming out will decrease their happiness substantially, but I am arguing that it is worth the chance in most non-extreme cases (i.e. where your life would not be in immediate danger etc) coming out, for you will only ever be uncertain as to how you would feel if you never came out, and may in fact have missed out on a truer and deeper happiness in life, even if you say you are happy now. xx