TF Genetics

Here's something I've always found puzzling...
...how can Sunstreaker and Sideswipe be brothers when they share none of the same attributes and have different transforms, whilst Red Alert (who is a virtual carbon copy of Sideswipe) isn't 'related' despite the obvious genetic similarities.
Also using the same logic, why aren't Ratchet and Ironhide, Trailbreaker and Hoist, or even Starscream, Skywarp and Thundercracker considered brothers, when to all intents purposes they are the same robots!
Just a thought, but has anyone got any ideas?
...how can Sunstreaker and Sideswipe be brothers when they share none of the same attributes and have different transforms, whilst Red Alert (who is a virtual carbon copy of Sideswipe) isn't 'related' despite the obvious genetic similarities.
Also using the same logic, why aren't Ratchet and Ironhide, Trailbreaker and Hoist, or even Starscream, Skywarp and Thundercracker considered brothers, when to all intents purposes they are the same robots!
Just a thought, but has anyone got any ideas?