Why do I have to tell my parents that I am queer but my straight friends do not have to tell their parents that they are straight?

Because of what's called heteronormativity. General society considers heterosexuality to be the "default," so people are generally assumed to be straight and thus don't need to announce their straightness to everyone. Coming out is when those of us who aren't straight correct the assumptions that we are. Similarly, there is cisnormativity in which everyone is assumed to have the same gender identity as the sex they were born as, and amatonormativity which assumes that a heterosexual amorous relationship is the end-all-be-all goal for all humans. Because of these assumptions, we have to "come out" and tell people the reality of who we are. Otherwise, they'll be left believing we're something we aren't. That may be preferable sometimes, especially if your well-being may be at risk if you came out. Many people choose to wait until they are financially independent before telling their parents, just in case. These things shouldn't happen. We should all be accepted and validated for who we are, and we should never be assumed straight or cis-gendered or treated like aliens if we want something other than a fairytale romance. Unfortunately, general society isn't to that point yet, and it's up to us to help get it there. Just remember: if you feel it, it is real and valid, no matter what others try to tell you.

This is referred to as heteronormativity. Our social considers that anyone is heterosexual unless they specify they aren't.

it's a double standard! we live in what's called a heteronormative society. it's a big word, but basically it means that in our society, "straight" is considered the default. so everyone assumes you're straight until they're told otherwise. it's really unfortunate, and people are slowly starting to challenge that belief, but it takes a long time for things to change. in the meantime, you can do your part to educate others about how straight isn't the default, so that everyone can teach their future children that and we can go on to make our world a more accepting place.

Because of heteronormality. Hetersexual and cisgender are automatically assumed to be the 'default', even though they are not. Basically, most people assume others to be cis and straight, unless otherwise told so.

I think, in our society, it is assumed that people are straight. And because of that, your parents probably assumed the same for you. Ultimately, it is YOUR choice to tell them otherwise. If you want them to know who you are, and how you identify as a person, that is completely up to you.

Since LGBTQ+ identities are a minority, there is this idea that LGBT people should make announcements rather then simply living their life naturally, without making a big deal about it. Straight people are the majority, so people take it for granted that it's the "default" identity. But you are free to live your identity in any way you prefer. You're not obliged to come out, if you don't want to. You can just live your life, follow your heart, do what makes you feel good, without making a big deal or making big announcements. They will still find out who you are, unless you actively try to hide it, but you'll have your chance to deal with it in the way that feels most natural to you.

Because we live on a society that expect the "default behavior" and want to know what is considered outside of it.

In all honesty you don't have to. This is entirely your choice. Allow yourself space and time in order to feel comfortable having that conversation if you so wish but remember there is no rush.

Sadly, because we live in a heteronormative society. This means that in our society, being straight and cis are considered default, and for this reason, most people have a habit of assuming people's gender and sexual/romantic orientations. That's why straight cis people don't have to come out, everyone already assumes that's their identity.

We live in a society that is predominantly heterosexual and cisgender. Because of this, our society assumes being straight is the sexual orientation that we should all be. This is something that is ingrained in our society. For example, a heteronormative assumptoin would be that a man will grow up straight and marry a female. These assumptions form the closet that so many people in the queer community may choose to come out of.