Following the handover, a period of 50 years was allowed for the two areas to bridge the gap in terms of culture and lifestyle, so integration could be achieved smoothly afterwards.
However, with extensive bonds being already formed, Hong Kong is now faced with a large influx of mainlanders and will find it hard to cope with more new arrivals.
The problem can be attributed to the rapid door-open policy.
One of the prime examples is the huge demand for maternity services in our city. Our advanced medical system is a magnet for mainlanders who want to give birth here. As a result, we are seeing rising numbers of heavily pregnant mainland women competing with locals for a place in our hospitals.
When Hong Kong was still a British colony, the government could shut the door easily on these mainlanders, but after the transfer of sovereignty, boundaries became more blurred.
Despite some people's claim that Hong Kong was more prosperous before the handover, the city still has a better medical, education and legal system which appeals to many mainlanders.
But Hongkongers are feeling the pinch now. The shortage of baby formula, maternity services and housing are caused by a strong demand for a limited supply.
It is not that we do not welcome people from the mainland, but Hong Kong does not have the capacity to accommodate all those who want to enjoy our services. And that is why we need to maintain the 50-year buffer period so we can be ready to meet their needs.
But is it possible to halt this movement? Probably not. The construction of the high-speed rail link and the Hong Kong-Zhuhai-Macau bridge will make it even easier for cross-border travel.
The inconvenient truth is that we have no choice but to adapt to this changing environment. The old days are gone.