How can you track a person?

Hi everyone! Long story short, my dad left us when I was a kid and moved to Australia. The problem is that I've recently been diagnosed with a bunch of gut issues that I've never had before, even though I don't drink or smoke, exercise regularly, and generally lead a very healthy lifestyle. My doctor is shocked to say the least, because my maternal relatives have never had this, and this diagnosis came out of nowhere. I need to know what my paternal relatives have so I don't get any bad news in the future if my health continues to deteriorate.
So. I know this:
I know my dad's full name.
I know he works for Doctors Without Borders as a psychologist.
He lives in Australia.
I have his old Hotmail email address. I sent him a very polite email asking for this information, but he never responded. But I haven't received any undeliverable emails either. That's... all I know. Maybe someone can tell me where to go?