1. the way they think
Gulliver says that the Yahoos "found as near a resemblance in the disposition of our minds." This means that they resembled (or were like) each other when it came to how their minds worked. Gulliver does not talk about family relationships at all. He does says that they were different in terms of "strength, speed, and activity, the shortness of my claws."
2. replace "ran" with "sprinted"
This is the best option because it adds more specific detail to the way the girls are moving without changing the meaning of the sentence. Changing from track to neighborhood or P.E. to track meet would alter the location and purpose completely. Also changing "around" to "through" would indicate that the girls are not actually running on the track but rather across it as though they had to get from one place to the next.