What is the genetics behind a unibrow?

All over the place!: Most people with unibrow are normal & healthy but simply have a genetic trait that causes (or allows) eyebrows to grow together. Selma Hayek, the actress, has a unibrow, not just in her role in Frida, but in real life. Because the gene(s) that promote "unibrow" may be inhibited by genes that suppress it, there's only a small chance that her daughter will also grow one. Hope this info helps!