HI L.,
This has been an on going conversation in my house as well. I am vegetarian and my husband and my children are not.
I have no problems with my boys taking soy (or eating meat for that matter). My husband did some research and was concerned about our boys and their soy intake, as my oldest has a dairy allergy and I am not a fan of cow's milk for a plethora of reasons.
Here is what I found by researching. Not everything here is my own words, and I can site it for you if you'd like more information.
For more than 35 years, soy based infant formula has been a safe, healthy way to support normal growth and development of infants.
There was a study that was conducted at the University of Iowa that supported the safety of soy-based infant formula. The study monitored the effects of soy-based infant formula on the growth and development of children and found that there were no significant differences in terms of growth and development between those given soy-based formula and those given cow's milk formula. Additionally, researchers conducted a multi-generation feeding study in rats aimed at examining the the long-term health consequences of early consumption of soy protein. The number of off spring, gender rations, birth weights, health and general appearance of soy-fed rats were the same as those milk fed controls.
The negative assertion has never been observed in any study involving humans.
Also, some people hear that there are phytoestrogens in soy and automatically think "estrogen" (why wouldn't they? The word is the same and sure, too much estrogen sounds bad). However, a plant estrogen is not the same as a human estrogen and really shouldn't have the same name. So, there is a lot of "scare tactics" online about the so-called dangers of soy. Most of what I found in the negative campaign against soy could not be substantiated by science.
Having said that, we feed our boys rice AND soy milk.
I have a lot of information if you'd like more. I have a lot of people ask me about these so-called dangers of soy, so I consider myself a soy nerd with all the research I have done.
I hope this helps.
B.