Their dads are a mystery to avoid shipping wars, so these kids are shipping-neutral. The designs were inspired by the mothers only.
Fully detailed personality profiles of these can be seen in the original source link.
NOTE: Some of these designs have changed over time, such as hair styles and cutie marks. Also, the breaking the 4th wall joke only works with Deviantart’s green background.
Tempest: RD’s son
Radiance: Rarity’s daughter
Bismarck, Bucky: Applejack’s boys
Flora, Peach Cobbler: Fluttershy’s girls
Berry/Cherry Pie: Pinkie’s twin son and daughter
Orion, Andromeda: Twilight Sparkle’s son and daughter
Just like the actual show. The designs were meant to be as canon-like as possible.
You don’t see gradient ponies, ponies with spots, stripes, and such in Ponyville. That’s all fan-made. Few characters even have more than one hair color. I didn’t want these kids to look over-designed.
Besides, there’s a lot more to the colors than you think. Nearly every color chosen was based off of family, like Andromeda’s hair being the same color as one of Twilight’s stripes. Every hue was specifically chosen.