I'm going to put my sister on read because I didn't feel it needed a response
Why would you ignore your sister like that?
Usually, when she write on me she usually just links to some picture and ask me if I saw it.
Typically even simple communication like sending pictures should get a response. If they're sending you stuff then they clearly care about your opinion and likely want a response.
I'm a human being who is not interested in what she says and I'm not going to reply to her.
You should try be considerate of their feelings. If you leave them on read they probably feel like they're being ignored. If you don't want to respond then be honest about why so that they can at least use their time in a different manner instead of waiting around for you.