In your case Yelizaveta, you’re entering a big field as you noted that is also one of the five fastest growing engineering disciplines so there will be no shortage of opportunities for you to specialize in well-worn rabbit holes as well as new ones during your Junior and Senior years.
With that in mind, there’s no need to be anxious about selecting an area of focus now – the first year or two for most engineering disciplines are full of prerequisites such as math, physics, chemistry, biology, and a few intro classes in your major to help you make that decision. Just keep your advisors and counselors in the loop about what you’re thinking of for a major, and together you should decide late in your Sophomore year.
On your specific comment about genetics and animals I have to claim ignorance, because as a retired mechanical engineer I thought bio-engineers designed interior and exterior human and probably animal prosthetics. Maybe genetics is a part of that I just wasn’t aware of.
Attached is a link to a YouTube video of a young bio-engineer interview where he describes what he and his coworkers do. Thought you might enjoy. Good luck.