Henry III (1379 - 1406) was the son of John I of Castile and succeeded him as King of Castile and León in 1390. He married Catherine (in English, or Catalina in Spanish) the daughter of John of Gaunt and his second wife Constance (in English, or Constanza in Spanish), a daughter of King Pedro I), and their son became John II of Castile.
... out with 29.5% under the age of 18, 6.7% from 18 to 24, 33.6% from 25 to 44, 20.6% from 45 to 64, and 9.6% who are 65 years of age or older. The median age is 35 years. ...