based on this video: https://youtu.be/TGLYcYCm2FM?t=106 , checks how come there are 10% left handed people, if all combinations of them are above 10%

leftHandedStatisticsCheck

import java.util.ArrayList;
import java.util.Random;

//based on this video: https://youtu.be/TGLYcYCm2FM?t=106
// checks how come there are 10% left handed people, if :
// left-male + right-female = 17% left handed
// right-male + right-female = 10% left handed
// right-male + left-female = 22% left handed
// left-male + left-female = 25% left handed

public class Main {
	private static final int GENERATIONS = 100;
	private static final int POPULATION_SIZE = 10000;

	private static class Person {
		boolean isLeftHanded;

		public Person(final boolean isLeftHanded) {
			super();
			this.isLeftHanded = isLeftHanded;
		}

	}

	public static void main(final String[] args) {
		final ArrayList<Person> males = new ArrayList<>(POPULATION_SIZE / 2),
				females = new ArrayList<>(POPULATION_SIZE / 2);
		final Random r = new Random();
		for (int i = 0; i < POPULATION_SIZE / 2; ++i) {
			males.add(new Person(r.nextInt(10) == 0));
			females.add(new Person(r.nextInt(10) == 0));
		}
		int leftTotal = getCountOfLeftHanded(males, females);
		System.out.println("before, left handed count:" + leftTotal + " out of " + POPULATION_SIZE + " which is "
				+ 100 * leftTotal / POPULATION_SIZE + "%");
		for (int i = 0; i < GENERATIONS; ++i) {
			for (int j = 0; j < POPULATION_SIZE / 2; ++j) {
				final int chanceToGetLeftHandedChild;
				final int chosenMaleIndex = r.nextInt(POPULATION_SIZE / 2 - j),
						chosenFemaleIndex = r.nextInt(POPULATION_SIZE / 2 - j);
				final Person chosenMale = males.get(chosenMaleIndex), chosenFemale = females.get(chosenFemaleIndex);
				if (chosenMale.isLeftHanded)
					if (chosenFemale.isLeftHanded)
						chanceToGetLeftHandedChild = 25;// both left
					else
						chanceToGetLeftHandedChild = 17;// male-left,
														// female-right
				else if (chosenFemale.isLeftHanded)
					chanceToGetLeftHandedChild = 22;// male right, female left
				else
					chanceToGetLeftHandedChild = 10; // both right
				// removal of previous generation of male and female, and check
				// the next couple
				males.remove(chosenMaleIndex);
				females.remove(chosenFemaleIndex);
				// birth of male
				int roll = r.nextInt(100) + 1;
				if (roll <= chanceToGetLeftHandedChild)
					males.add(new Person(true));
				else
					males.add(new Person(false));
				// birth of female
				roll = r.nextInt() + 1;
				if (roll <= chanceToGetLeftHandedChild)
					females.add(new Person(true));
				else
					females.add(new Person(false));
			}
			leftTotal = getCountOfLeftHanded(males, females);
			System.out.println("generation:" + i + " left handed count:" + leftTotal + " out of " + POPULATION_SIZE
					+ " which is " + 100 * leftTotal / POPULATION_SIZE + "%");
		}
		leftTotal = getCountOfLeftHanded(males, females);
		System.out.println("after, left handed count:" + leftTotal + " out of " + POPULATION_SIZE + " which is "
				+ 100 * leftTotal / POPULATION_SIZE + "%");
	}

	private static int getCountOfLeftHanded(final ArrayList<Person> males, final ArrayList<Person> females) {
		int totalLeftHanded = 0;
		for (final Person person : females)
			if (person.isLeftHanded)
				++totalLeftHanded;
		for (final Person person : males)
			if (person.isLeftHanded)
				++totalLeftHanded;
		return totalLeftHanded;
	}

}