We do not know what makes a person homosexual or heterosexual. To the best of our knowledge, at least part of a person's sexuality is determined before they are born. It is normal at your age to like people of the same sex very much. For instance, it is normal to have a best friend of the same sex. This does not make a person homosexual, just as having a person of the opposite sex as a best friend does not make a person a heterosexual.
Sexuality is a response that people learn about throughout their life.
Individuals at different ages have feelings about sexuality that they learn to understand better as they grow older. As you grow older, you will have many different questions about sexuality and your feelings. Even adults may have questions about why they feel the way they do about sexuality. You do not have to be concerned with who you like or love. If you love someone of the same sex, your brother or sister for example, that is just fine.