so like this
$sql = "INSERT INTO brothers(name, major, major2, minor, minor2, minor3, email, number, password, phone, address, city, state, zip, birthdate, bigbrother, littlebro, little2, little3, little4)
VALUES('$name', '$major', '$major2', '$minor', '$minor2', '$minor3', '$email', '$number', '$password', '$phone', '$address', '$city', '$state', '$zip', $birthdate', '$bigbrother', '$littlebro', '$little2', '$little3', '$little4');") or die (mysql_error());
echo $sql;
or
$sql = mysql_query("INSERT INTO brothers(name, major, major2, minor, minor2, minor3, email, number, password, phone, address, city, state, zip, birthdate, bigbrother, littlebro, little2, little3, little4)
VALUES('$name', '$major', '$major2', '$minor', '$minor2', '$minor3', '$email', '$number', '$password', '$phone', '$address', '$city', '$state', '$zip', $birthdate', '$bigbrother', '$littlebro', '$little2', '$little3', '$little4');") or die (mysql_error());
echo $sql;