Write SQL query to solve given problem: What is the favourite movie genre for audiences of age 18?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T1.genre FROM movies2directors AS T1 INNER JOIN u2base AS T2 ON T1.movieid = T2.movieid INNER JOIN users AS T3 ON T2.userid = T3.userid WHERE T3.age = 18 GROUP BY T1.genre ORDER BY COUNT(T1.movieid) DESC LIMIT 1