Inclusion Criteria:  Infants and young children: age 4 months, 6 months, 12 months, and 2 years old; term single birth (37-42 weeks of gestation); health inactive disease; normal Griffiths developmental assessment; natural vaginal delivery or social cesarean section; Apgar score greater than 7 at birth for 1 or 5 minute.  Exclusion Criteria:  Infants and young children: birth weight < 2500 g; premature or multiple births; prenatal ultrasonography indicating intrauterine growth retardation; severe organic diseases of the baby after birth that have been hospitalized for treatment; congenital malformations or diseases affecting the feeding of the baby (cleft lip and palate, metabolic diseases, etc.).