Most people born with the surname Chandler in modern times are descended, in the male line, from men in England who worked as a chandler, making and selling candles. Until about 1350, surnames were only used by the wealthy, and were usually inherited by only the eldest son, along with the family property. The poor - most people at that time - had no need for a surname because they had no land to inherit. It was during the years 1350 to 1450 that the use of hereditary surnames became common throughout the English population. This naming - often by trade (e.g. Baker, Smith, Chandler), sometimes by location (e.g. Hill, Marsh, or the name of a town or village), occasionally by appearance (e.g. Long, Small) - would have happened village by village throughout England. Consequently, most of the people acquiring the surname Chandler in this way would not have been related to each other - they would only have been occupied in the same trade.

Candles - of vital importance in an age without electricity - were made either of wax (for churches and the wealthy) or tallow (for general use). Tallow is obtained from suet (the solid fat of animals such as sheep and cows), and is also used in making soap and lubricants. The Tallow Chandlers, like many other tradesmen, formed a guild in London in or around 1300 for educational, promotional and charitable purposes. The Tallow Chandlers also dealt in vinegar, salt, sauces and oils. Later, the term 'chandler' was used for corn chandlers, and for ships' chandlers who sold most of the fittings and supplies for boats, as well as the candles. In the 18th and 19th centuries, the term 'chandler' was often used simply to mean a grocer.

Some people born with the Chandler surname may descend from followers of William, Duke of Normandy, who ruled England from 1066 to 1087 - bearing names like Reginald le Chandeler, who appears in a survey of London conducted in 1273. The origin of the name is the same - the French for candle being chandelle.

The Chandler DNA Project (see below) has so far identified 105 genetically distinct lines around the world. It is highly probable that - at least as far back as the 1200s - the ancestors of all these testees lived in England. The term 'England' is used deliberately, in preference to 'Britain' or the 'United Kingdom', because the geographic origin of the surname Chandler is firmly in England. We have been wondering how many genetically distinct lines we will ultimately find. A definitive answer can't be given now, but a general feel can be obtained from the following analysis.

As stated above, some Chandlers - a minority - descend from one or more le Chaundelers who migrated to England from Normandy around the year 1200. Most Chandlers, however, descend from people who gained their surname because they were candle-makers in the period 1350 to 1450 when hereditary surnames became common in England. This adoption of surnames was a slow process, taking around 100 years, spreading from the towns into the countryside, and from the south of England to the north. The types of names favoured for adoption varied from area to area - some regions, especially in the west and north of England, tending to prefer locative names (e.g. Hill, Marsh or the name of the village or town where they lived), others favouring occupational names (e.g. Baker, Butcher, Chandler), others selecting patronymic names (e.g. Johnson, Jackson, Richardson) - and the choices made also varied between social classes.

After the 'Black Death' plague (about 1350), the population of England had shrunk to 2.5 million. The 1881 Census of England (before significant immigration from Britain's colonies) shows that Chandlers were 0.0355% of the population. There seems no good reason why this should not be about the same percentage as in 1350, which would yield 888 Chandlers. Assuming a 50/50 split, 444 of these would be male Chandlers. Assuming that possibly 44 of these descend from a single Norman (or several related ones) named le Chaundeler and his (their) descendants during the 150 years they had been in England, that leaves around 400 males who got their surname from the Chandler trade (in areas where that was the practice). Not every candle-maker in England took the Chandler surname; he might become, say, a Johnson (son of John) if that was the regional or personal preference, even though he made candles. Now, the question would be, in all the households where the main breadwinner was a Chandler by trade and chose to give his family the surname Chandler, how many males, of all ages, would have been in each household? Assuming the range was 2 to 4 Chandler men in each family, we are left with 100 to 200 different genetic lines plus the le Chaundeler line. It would probably be at the lower end of that range. The families acquiring the name were not necessarily the nuclear families we know today. They were more likely to be extended families that included miscellaneous 'family' members who would also pick up the Chandler surname. Some lines may have since become extinct for lack of male offspring.
Analysis of the names in the 14th Century English Poll Tax returns also suggests that the number of genetically distinct Chandler lines, now spread around the world, is closer to 100 than 200.