m_i 값이 안바뀌는 이유가 뭔가요?

//
//  main.cpp
//  inheritance_ex01
//
//  Created by Kevin on 04/10/2019.
//  Copyright © 2019 Kevin. All rights reserved.
//

#include <iostream>
using namespace std;

class Mother { // basic class
private:
    int m_i;
    
public:
    //Mother() {}
    
    Mother(const int& i_in) : m_i(i_in) {
        std::cout << "Mother constructor" << std::endl;
        std::cout << "m_i " << m_i << std::endl;
    }
    
    void setValue(const int& i_in) {
        std::cout << "i_in " << i_in << std::endl;
        m_i = i_in;
        std::cout << "m_i " << m_i << std::endl;
    }
    
    int getValue() {
        return m_i;
    }
};

class Child : public Mother {
private:
    double m_d;
    
public:
    Child(const int& i_in, const double& d_in) : Mother(i_in), m_d(d_in) {
        std::cout << "Child constructor" << std::endl;
        Mother::setValue(i_in);
    }
    
    void setValue(const int& i_in, const double& d_in) {
    }
    
    void setValue(const double& d_in) {
        m_d = d_in;
    }
    
    double getValue() {
        return m_d;
    }
}; // derived class

int main(int argc, const char * argv[]) {
    Mother mother(512);
    std::cout << mother.getValue() << std::endl;
    
    Child child(1024, 2048);
    std::cout << "m_i value : " << mother.getValue() << std::endl;
    // 왜 512인가요?
    std::cout << "m_d value : " << child.getValue() << std::endl;
    
    return 0;
}