Mankind has colonized 28 planets between 7 and 40 light years from Earth. It was not done by sending people or even genomes in space-ships. Once the principle of quantum transmission based on mass-less particle states had been discovered in 2030, it became a relatively simple matter to transmit data instantaneously. All that was required was a transmitting/receiving station at the remote location. By 2040, astronomical inter-stellar planetary exploration had established the existence of a number of planets suitable for colonization (not by humans, of course, but by organisms with quasi-human brains and bodies suited to the varying climatic, gravitational and biochemical environments).
By 2050, the mass of a remote transmitting/receiving station had been reduced to 350 grammes, and photon-driven motors could propel such payloads at up to 70% of the speed of light in a vehicle weighing little more than two kilos in total. On arrival in the neighbourhood of a suitable planet, the station (with real-time control from Earth), establishes itself in orbit and surveys the destination planet. About one quarter of destination planets tend to fall within the range of sustainable parameters for quasi-human life. Having established viability (vehicles arriving at unviable planets are simply abandoned), the station descends to the surface of the planet using a combination of tiny chemical thrusters (accounting for most of the mass of the vehicle) and magnetic gravity brakes (described before his death in 2012 by Stanford Ovshinsky, but not realized until 2020). The presence of substantial quantities of iron or other magnetic materials is a prerequisite for planetary colonization due to the impossibility of physical descent from orbit in the absence of magnetic fields. The other unavoidable requirement is that there should be bodies of surface water and/or certain liquid hydrocarbon compounds.
Reaching (ideally) an area of water on the surface of the planet, the hard-shelled, virtually indestructible station carries out more detailed analysis of its surroundings, and uses instructions received back from Earth to begin genetically-driven biochemical construction of self-replicating cells using local materials which are released into the surrounding liquid and follow a process of development not dissimilar to the origins of life on Earth, except that of course it is pre-planned in the organism's genome and happens very rapidly. There are losses from local conditions, but most of the implantations are successful, and within about one Terran year adult organisms will reach land. They are heavily programmed to ensure the safety of the station, which is then able to begin production of locally viable quasi-humans (Remote Cognitive Representations – RCRs), again based on instructions from Earth, employing locally available chemicals and minerals.
Once viable quasi-human RCRs exist the risks of loss from local conditions become small, and most colonies are then successful. (The RCRs are fully human in cognitive terms, indeed they are effectively copies of existing humans on Earth and are directly controlled, cognitively speaking, by their remote progenitors via the instantaneous link between the receiving and transmitting stations; local communication takes place by wireless at the speed of light, so delays are not significant.) Altogether, about 10% of missions to planets which have been identified as likely hosts result in successful colonies.
Clearly, the time-scale of colonization depends on the distance to be travelled by the station initially, so that the furthest successful colony in 2160 is only 55 light years from Earth. More than 20,000 missions are still in transit, however, some to destinations as far away as 500 light years, and it is expected that new colonies will be added at an increasing rate in future. However, no planet has yet been discovered which could reasonably be inhabited by humans in their Terran form.
Individuals who 'father' successful remote organisms inhabit them close to 100% of the time, and play little part in continuing life on Earth, at least until a colony is breeding on its own account, and this is something which has so far happened only in one or two of the earliest cases. Social life remains as important on colony planets as it is on earth, and the groupish instincts and institutions which developed on earth for governance, socializing and recreation are fully deployed on colony worlds through Remote Cognitive Collectives (RCCs). Individual RCRs tend to be widely scattered across a new world in the early stages of colonization and physical meeting is awkward; in any case, by the late 21st century when the first colonies began to take shape, most social, business and governance interaction had long since migrated to RCCs.