Blood is a very important fluid in our body that helps keep us healthy and alive. Sometimes, when people are sick or get hurt really bad, they may need blood from another person to help them get better. But, before these people can get blood from someone else, the blood has to be tested to make sure it is safe to use.
In the past, some people who had certain illnesses in their blood gave blood to others, and it made them sick too. One of these illnesses is called HIV, and it can be spread from one person to another through things like unprotected sex or sharing needles. This is why the people who test blood have decided to put some rules in place to keep blood as safe as possible.
One of these rules is that men who have sex with men are often not allowed to donate blood. This is because, statistically, men who have sex with men are more likely to have HIV in their blood than other people. But, it's important to note that this rule is not because of someone's sexual orientation, but because of the potential risk of HIV transmission.
It's not fair, and it can be very frustrating for people who want to donate blood but can't because of this rule. But, it's important to remember that the people who test blood want to make sure that the blood that gets used is as safe as possible to avoid any potential harm to the person receiving the blood transfusion.