The theme of the book is the influence of family background on the development of bilingual child. This problematic is very wide, nowadays, because all over the world revises lots of mixed marriages with mixed nationalities who raise their kids bilingually. The book is divided into two sections: theoretical section and practical section. Theoretical section deals with a specific description of bilingual families, methods used during education of bilingual kids and myths about bilingualism. The practical part consists of a case study of two girls: one is bilingual from birth, because one parent is foreigner and other has been learning second language for two years already. Girls are about the same age, there is only few months' difference between them. The comparison will be oriented on production in Slovak and also English language.