It's NOT what the kid is saying but what the OLD MAN says that should concern you.
Thanks to what the elderly figure of the day care said to you, it's possible to understand the affinity between the two mating pokémons.
Same species with different ID numbers: Chance of getting an egg; 70%
| Statement; "The two seem to get along very well!"
Same species with same ID numbers: Chance of getting an egg; 50%
| Statement; "The two seem to get along"
Different species with different ID numbers: Chance of getting an egg; 50%
| Statement; "The two seem to get along"
Different species with same ID numbers: Chance of getting an egg; 20%
| Statement; "The two don't seem to like each other" Different Egg
Groups: Chance of getting an egg; 0%
| Statement; "The two prefer to play with other Pokémon more than with each other."
Also, due to the fact that you own Ralts from different countries, you have a higher chance of obtaining SHINY EGGS.
This is a process known as Masuda Method.
To sum it up:
It occurs whenever Pokémon of differing real-world geographical origin are bred.
Here are links with more info on the matters that interest you
Masuda Method
Day Care
also, this question may be helpful to you, so give it a look when you have time.
Hope I helped!