Cow's milk is bad, no matter what age. Soy products are not good as well, unless they are fermented soy.
Dairy has been advertised to us and we have been bred to believe it's good for people. This is not true. We do not have the nutritional requirements of bovines. "studies" have been done to show that dairy is good for us. Well, who funds those studies' that the fda touts as proof? Dairy farmers, people with some stake in the industry. Same goes for phamecutical companies. For various sources, use google. Check who pays for the site, however, some is just propaganda for and against. Never believe what someone says if they are paid to say it!
For optimum health, when weaned, children should drink distilled water or no sugar added 100% fruit juices. Adults may drink tea as well.
If you must have "dairy" try rice or almond milks. Almond tastes pretty good!