LGBT people are a distinct community within the general population with distinct opinions.
Why do you think polls are weighted by age, gender, region and voting record? Because those are distinct demographics with distinct views.
Poll 1,000 people aged 18-24 and they'll have different views to those aged over 65.
Poll 1,000 LGBT people and they'll have different views to 1,000 straight people.
1,000 women will have different views to 1,000 men and as we saw in the EU referendum people in Scotland have different views to those in England and Wales on Brexit.
Hope that helps! always happy to teach you about politics as well as LGBT issues.