Relation between class_Size and inheritance

#include <iostream>
using namespace std;

class Base
{
    int first_int;           //size of int is 4 byte
    int second_int;       //so size of Base class is 8 byte
};

class derived:public Base
{
    int derived_member;
    int another_derived_member;
    int new_member;
};

class home
{
    Base base_1;
    Base base_2;
};

int main()
{
    cout << sizeof(derived) << endl;     //the size of derived class is (8+12=20) byte
    cout << sizeof(Base)    << endl;
    cout << sizeof(home)   << endl;      //the size of home class is (8+8)=16 byte
}

OUTPUT:
20
8
16