We investigated the probabilistic evolution of five pairs of trans-Neptunian objects in close orbits. All pairs belong to the cold population of the classical Kuiper belt. For each trans-Neptunian object, 1000 clones were generated within the limits of errors in determining the orbital elements. Numerical modelling was performed using the Orbit9 software included in the OrbFit. In the modelling, perturbations from eight major planets and the dwarf planet Pluto were taken into account at 10 Myr in the past, while perturbations from only four giant planets were taken into account at 200 Myr in the past. We used two methods to estimate the ages of pairs. The first method searched for moments of low relative-velocity close encounters of clones belonging to different objects in the pair. The second method analysed the moments of time when the minimum value of the Kholshevnikov metric was reached between clones of different trans-Neptunian objects. Low relative-velocity close encounters were not recorded for the pairs under consideration. On the basis of the analysis of the moments of reaching the minimum values of the metric, we obtained age estimates for all five pairs. The minimum age of +1.0 42 +147 -31 kyr was recorded for the pair 2013 SD101 - 2015 VY170. A maximum age estimate of 2.2 -0.7 Myr is obtained for the pair 2003 QL91 - 2015 VA173. All five pairs of trans-Neptunian objects considered can be classified as young. This paper is based on a talk presented at VIII Bredikhin conference.