jboss-seam-2.1.0.SP1 Hibernate version:3.3.2

Project is generated with seam-gen. Following setup works fine but I am confused with the generated SQL.

I have the following tables.
-------------------------------
User
Patient
Doctor
Supervisor

Respective hibernate objects
---------------------------------
@Entity
@Table(name = "user")
@Inheritance(strategy = InheritanceType.JOINED)
User

@Entity
@Table(name = "patient")
Patient extends User
// id is not defined here.

@Entity
@Table(name = "doctor")
Doctor extends User
// id not defined

@Entity
@Table(name = "supervisor")
Supervisor extends User
// id not defined

When I load Patient list, I see a join between a patient class and user class which totally makes sense. But when I view User list, I see the following SQL.

select
user0_.id as id0_,
user0_.email as email0_,
user0_.passwd as passwd0_,
user0_.first_name as first4_0_,
user0_.last_name as last5_0_,
user0_.gender as gender0_,
user0_.dob as dob0_,
user0_.phone as phone0_,
user0_.fax as fax0_,
user0_1_.contact_name as contact3_1_,
user0_1_.contact_phone as contact4_1_,
user0_1_.contact_email as contact5_1_,
user0_1_.contact_fax as contact6_1_,
user0_1_.display_order as display11_1_,
user0_2_.contact_name as contact3_2_,
user0_2_.contact_phone as contact4_2_,
user0_2_.contact_email as contact5_2_,
user0_2_.contact_fax as contact6_2_,
user0_2_.status as status2_,
user0_2_.display_order as display11_2_,
user0_3_.status as status6_,
user0_3_.contact_name as contact4_6_,
user0_3_.contact_phone as contact5_6_,
user0_3_.contact_email as contact6_6_,
user0_3_.contact_fax as contact7_6_,
case
when user0_1_.id is not null then 1
when user0_2_.id is not null then 2
when user0_3_.id is not null then 3
when user0_.id is not null then 0
end as clazz_
from
user user0_
left outer join
doctor user0_1_
on user0_.id=user0_1_.id
left outer join
patient user0_2_
on user0_.id=user0_2_.id
left outer join
supervisor user0_3_
on user0_.id=user0_3_.id limit ?

Why is it doing a left outer join with doctor, patient and supervisor entities when I load user list? Is this the normal behavior? If it is, what should I do to prevent the joins and only load user list? I guess this makes sense for other inheritance strategies.