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Since you only mention three traits, it sounds like your twins are still children and that one of them got a wish to be a Journalist. When they are children, you don't have to accept the wishes for their Lifetime Wish. If the one you want doesn't pop up during childhood or the teen years, you will be able to choose it when your Sim becomes a Young Adult. At that point, you'll get to choose from all of the Lifetime Wishes, no matter what their traits are.
For your Astronaut, the Handy trait will become available at the Teen stage. Not all traits are available in the younger stages, but they show up later when your Sim has birthdays.
For your Surgeon, Light Sleeper probably isn't a great choice. All it does it make them wake up during the night for no apparent reason and you have to send them back to bed. Workaholic would be a good trait for a Surgeon. You can change traits using testing cheats as long as you're not playing one of our challenges. First, press and hold the Shift, Ctrl, and C keys on your keyboard. The screen will darken a little and you can type on it. Type "testingcheatsenabled true" without the quote marks and press Enter. The screen will go back to normal and testing cheats are turned on. Next, hold down the Shift key and click on the Sim whose traits you wish to change. An option to Modify Traits will appear. Click it and make whatever changes you want. When you're done, do the Shift-Ctrl-C again and type "testingcheatsenabled false" to turn off testing cheats.
I hope this helps. I'm also moving this over to Miscellaneous Help because I think that's a better place for it.