SELECT * FROM user_prof
WHERE gender = 0
AND user_id IN
    (SELECT following_id FROM followers)
    AND (SELECT user_id FROM user_prof
        WHERE gender = 1
        AND user_id IN
            (SELECT follower_id FROM followers));


SELECT * FROM user_prof WHERE user_id IN (
SELECT DISTINCT following_id FROM followers
    WHERE following_id IN
    (SELECT user_id FROM user_prof WHERE gender = 0)
    AND
    follower_id in (select user_id FROM user_prof WHERE gender = 1));

SELECT follower_id, following_id FROM followers
    WHERE following_id IN
    (SELECT user_id FROM user_prof WHERE gender = 0)
    AND
    follower_id IN (SELECT user_id FROM user_prof WHERE gender = 1);