I mean, maybe you can't sing right now - big deal. When was the last time you tried?
I bowl approximately once a year, and I've never had a lesson. You know what? It shows. I am a terrible bowler who can bowl a strike as often as might be expected from a statistical perspective.
If I wanted to get good at bowling, I would commit to it and work at it. I wouldn't just throw up my hands and say, "I can't bowl." I may never be a championship bowler, but I am sure that I could improve. How could I not, if I put some time and energy into it? I could even take some pointers from bowling pro to improve my game.
So with singing...seriously, if you actually tried it, you would find you could do it. But - maybe not at first. See, you have to learn how to use the muscles if you've never done so. I am not a good weightlifter, but that is only because I do not lift weights. I would get pretty good at it if I worked on it a few times a week, because I would be training my muscles. Likewise, you have to train your muscles for singing.
So there, you can sing! Do it, exuberantly and often. And if it's not too pretty - well, then maybe some lessons are in order. But not necessarily.