There's always an expert who knows more than you do, and is very willing to sell you a book to let you know how wrong you are. For parents, this has gone on for hundreds of years, and produced some rather strange advice …at least strange to our ears. Playing with a baby will spoil him. Never hug or kiss your children. Don't feed a baby at night. You should start toilet training at two months. A short child is the mother's fault. And babies should start eating like adults as soon as possible.
After World War II, commercial baby food producers as well as pediatricians drastically lowered the age at which they recommended babies start solids. Between the 1930s and the 1950s, much to the delight of Gerber and Beech-Nut, the average age at which parents introduced solids plummeted from 7 months to four to 6 weeks, according to various surveys. Sackett, the same guy who feared insufficient strictness would lead to socialist babies, was at the leading edge of this trend, writing in 1962 that breast milk and formula were “deficient,” and therefore babies should be started on cereal at 2 days of age. At 10 days, they could have strained vegetables, and by 9 weeks old, the little one would be eating “bacon and eggs, just like Dad!” Sackett also recommended giving babies black coffee starting at 6 months of age, to get them used to “the normal eating habits of the family.”
Read a roundup of the most outlandish advice from "experts" at Slate. Link