Soy is nature's protein. It's been eaten for thousands of years all over the world!
There was a faulty article based on bogus research some years ago about soy and cancer, and even though it was retracted, people still have it in their heads that soy causes cancer. In fact, high quality soy has a beneficial effect due to the presence of a cancer-inhibiting and epigenetic booster peptide. I educate in this area and can give people studies on it. It's highly researched at major universities, the NIH and more! Don't be afraid of it!
There's also a lot of folk tale stuff about it being an estrogen problem, giving boys breasts and so on. Nonsense. These are plant-based estrogens and not comparable to human estrogen.
And soy infant formulas have been highly regarded for decades. I work with one of the scientists who, as a young researcher, helped formulate Pro-So-Bee as an alternative to milk-based formulas.
What you want the best soy, use real soy rather than a processed derivative. You want mechanically processed soy rather than chemically processed. Once soy is processed with things like alcohol and hexane, the benefits decline because the peptide is weakened and doesn't survive digestion. It won't hurt your child necessarily, but it lacks the nutritional power of mechanically-extracted soy. I recommend a soy-based nutrition product that can be taken by itself or added to other things (yogurt, juice, milk, etc.).
It's also very easy to use tofu in other recipes - mixed with ricotta or cottage cheese in lasagna, in stir fry, in smoothies and much more. I have many recipes on this.
Once you get into heavily processed foods like soy "cheese" and tofu hot dogs, you have the same problems that we have in other processed foods, so read labels. Don't buy something loaded with a zillion ingredients and additives because they are worse for you - it's not the same as real, whole soy. Same as real pork or beef are better for you than chemical-laden hot dogs.