Complex sentence: Mudge's start in life did not augur well for a future in endurance running, after she was born with pedal defects; both of Angela's feet and one of her twin sister Janice's were pointing backwards.
Split into simpler sentences: Mudge's start in life did not augur well for a future in endurance running. Both she and her twin sister were born with defects in their feet; both of Angela's feet and one of Janice's were pointing backwards.