When you apply for the Green Card Lottery you must be able to meet certain requirements, one of these requirements is that you must be at least 18 years old to apply.
Of course this does not mean that you must be 18 years old to travel to the United States on a Green Card Lottery visa, you could be listed as a dependent of a winner of the lottery and travel to the United States as well.
However, there are requirements for who counts as a dependent.
First, the principal applicant, the person who is actually filing the form to the United States Department of State, must meet their own strict requirements.
Principal applicants must be 18 years of age or older as mentioned before, be from a country listed as an eligible country by the State Department, and they must either have the equivalent of a secondary education, or two years of work training followed by two years of work in a trade.
With those qualifications an adult can apply for entry in the Green Card Lottery. An important step here to remember is that when someone files for entry in the lottery they must list all of their dependents (whether or not they will be coming with the principal applicant).
For a person to qualify as a dependent of the principal applicant they must be either a spouse or a child. Spouses are defined as being a person who is in a monogamous (only two people), heterosexual marriage with the person who is applying for the lottery.
However, recent trends in legislation in the United States may change this law to include homosexual marriages as well.
Children are defined to be dependents who are not married, under 18 years old and legally related to the principal applicant.