Depending on your country of origin, and your trip destination, passports are necessary. It is your sole responsibility to be sure you have the correct documentation for all travel. If you are applying for a new passport or renewing an expired passport, please allow sufficient time to have your family member's passports processed. Passports issued to minors under the age of 16 are set to expire every 5 years. Some countries require that a traveler's passport be valid for at least 6 months beyond the dates of the trip. Check your expiration dates carefully!
You may find helpful information about obtaining passports for minors on the US State Department's website.
US citizens can also refer to www.state.gov or the applicable foreign consulate for further details.