There is no love in this. It is temporary attraction and pure lust. It has a negative impact on the individual. We should not conflate lust with love. @Charley
My gay friends would have a good laugh at that, haha. Gay relationships work just like straight relationships - there is lust and passion in the beginning, but sooner or later that begins to fade. What grows are feelings of attachment, admiration, appreciation, and all the other facets that comprise love. A couple of my friends (both guys) have been together for around 10 years. Their sex life is now very limited, but they love each other more than anyone or anything on the planet. They make each other feel happy and secure.
I take from your comment that you've not had gay friends before, and you may not have had much experience with love, as you would understand this to be the case in most relationships, gay or not. This isn't a criticism of you, but I feel you're making a strong statement based on a clear lack of evidence.
Suppose they today want to normalise being gay lesbian bisexual transgender queer, but what if in future some people are interested in children and want to have sex with them? Would you allow that?
What if tomorrow they raise voice to normalise incest relationships cuz of some shits fell in love with their sisters or brothers? Would you want incest relationship be common?
Conflating gay relationships with paedophilia and incest is just a non-starter, lol. Vedder said it quite well, but just to reiterate:
(In most cases) LGBT people simply want to have equal rights to straight people. That is, they want to be able to marry, have relationships, and be accepted in society as 'okay'. These relationships are between two consenting adults.
Paedophilia There are a few reasons why having sex with kids is illegal and immoral. Here are two.
1) Children are incapable of giving
informed consent. That is, because of their age, they don't have enough information available to them about the consequences of entering into sexual relations with others to be able to make a decision that is in their interests. As you said, MD, it is possible to convince children to do all manner of unspeakable things. This is precisely why it's a problem.
2) Children are not physically developed to the point where it is safe for them to have sexual relations. Subjecting a body that isn't yet sexually mature to sex acts can cause severe harm, both physically and mentally.
IncestPerhaps surprisingly, incest is, and has been for a long time, legal, across vast swathes of the planet. It seems many places are more willing to accept sexual relations between siblings than they are between members of the same sex.
It is illegal in many countries, however, either for religious reasons or because children borne of incestual relations have a significantly higher chance of genetic disorders.
The reason we don't see more incest is because it's just not a very common trait, in humans, to desire those in our families. People don't think 'Ooo I'd love to fuck my sister, but damn, it's illegal'. They just don't want to fuck their sister.
The differenceIn any case, incest and paedophilia are patently different issues to the rights of LGBT individuals - who are adults, capable of giving informed consent, and who will not produce offspring with genetic disorders - to have relationships and marry. Equating them is like someone saying 'Well if you eat chicken, why not eat human?'
Nature vs nurtureThere have always been records of same-sex orientations, across all cultures, for all of history. Sex with members of the same sex is also present across the animal kingdom. This suggests that it is at least partly a genetic trait. But even if it's more nurture than nature, so what?
In countries where homosexuality has long been tolerated or accepted, where gay relationships are seen on-screen and regarded as 'no big deal', has there been any huge crisis? Nope. In the UK, The Netherlands, Germany, France, US and more, while acceptance of homosexuality culturally has risen, the number of people identifying as gay, or bi, or queer, has remained pretty much steady. Small increases have been attributed to the fact that people feel safer, now, to admit their sexuality.
I'm not sure what sort of doomsday situation people are envisaging here, but at least in these countries, the result of accepting LGBT rights, regarding marriage and relationships, has been net positive. The only real harm that has been done has been by straight people, committing acts of violence out of fear and ignorance.