Did the boys return the horse because they were conscience-stricken or because they were afraid?

The most beautiful essence of this story is the fact that the boys were very innocent and meant no harm to anyone. They were just dreamy and wished to ride a horse. It pricked their conscience when they saw the clear hearted farmer, John Byro, who didn’t suspect them even once for stealing the horse. They were not afraid but were guilt-stricken when they met a pure-hearted soul like John, who couldn’t even think of people of their clan stealing, even after he said it was confirmed that the horse resembled his, just like twins. The children might have also been afraid of ruining the prestige and honour of their families.