why jobs doesn't list commands from script

I have a script that runs some programs in the background, but after running it, they are not listed by the command 'jobs'. Why is this?

(./m_prog -t m_prog1 m_config) &
(./m_prog  -t m_prog2  m_config) &
(./m_prog  -t m_prog3  m_config) &

But if I execute each one of them from the terminal, they do appear in 'jobs'

How can I get the same effect from commands run in a script?