As mentioned, some people may have sex with both men and women so no third party means required.
Hmmm ok if we dismiss animals as an example we cannot say being gay is natural and we cannot say being gay is unnatural. I brought animals in because you used the term 'natural'.
If you are saying natural means what is normal, then I do not agree. You may say having 4 fingers is normal, but saying liking women, or marmite, etc. is "normal" is a grey area. If there was 1 person in a million I might agree its abnormal, but when you get to 1 in 10 people its no more of an abnormality than being Buddhist.
Can you name a psychological problem which affects only homosexuals?
You cannot say ALL are capable of heterosexual acts, but we know SOME are. Why? Well why do you like men? (that's an assumption

), Why do some middle aged men take up golf? Personal preference/pleasure.
No, you see murdering and robbing would hurt others, sleeping with animals would hurt the animals. Even without religion we can see we would not want something like murder happening to us and so can relate to how others want to be treated.
I think the copulating in the streets thing is meant to come to pass... one of the signs I believe.
And if they keep behind closed doors is it ok?
Simply because a child is too young to be able to make decisions like that. They are easily led and 'consent' is not a term you can take seriously with anyone who can barely write their own name. This is for all children, not just boys.
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