What does the internet term biology mean?

In recent years, the misuse of the word "biology" is extremely serious. Words like "biological brothers" and "biological sisters" can be seen everywhere. In fact, "biological" means that the child was born in person, and parents can only call it "biological". 16-year-old girl hates her parents' partiality and strangles her biological sister with a scarf ... Defender put forward at the trial that "the defendant and the victim are biological sisters, who have lived together since childhood and have no resentment on weekdays ..." "Biological" refers to her own birth or her own birth, in other words, "biological" can only be used between parents and children, such as "biological daughter".

It is obviously wrong to say "biological sister" in the example, but it is right to write "biological sister" directly.