[devilbunny]

We must be using different forms of English, then, because they sound the same to me. “Thin” and “then” do not.

[umeshunni]

Indeed.

In US pronunciation, Then is ðɛn and Father is ˈfɑðɚ.

In UK (received), Then is ðɛn and Father is ˈfɑːðə(ɹ).

In Indian English, Then is ðɛn and Father is ˈfɑːd̪ə(r)

[ashishb]

Sorry I meant think and not then.