I have seen Levin Odhiambo's posts on Karua and Githu
If the only factor informing such is facial features, I take it with a pinch of salt. Facial features are like arithmetic. 24=8x3, 12*2, 4*6...
All of us have lookalikes!
What would be sensible would be claims in the line of Amalemba usually visited Gicugu and was dating the cutest villager or Githu's mum was a secretary at Lubembe's office.
It's interesting to note though, that Karua was born at the time(1958) when Amalemba was minister(very few Africans were ministers then, maybe Amalemba and Ohanga only)